MEMS having a cutout section on a concave portion between a substrate and a stationary member

ABSTRACT

A functional element includes a substrate which is provided with a concave section; a stationary section connected to a wall section that defines the concave section of the substrate; an elastic section which extends from the stationary section and is capable of stretching and contracting in a first axis direction; a movable body connected to the elastic section; a movable electrode section which extends from the movable body. The concave section includes a cutout section which is provided on the wall section. The stationary section includes an overlap section which is spaced with the substrate, and overlaps the concave section when seen in a plan view. At least a portion of the overlap section overlaps the cutout section when seen in the plan view, and the elastic section extends from the overlap section.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. application Ser. No.14/687,057, filed on Apr. 15, 2015, which claims priority to JapanesePatent Application No. 2014-086583, filed on Apr. 18, 2014. Bothapplications are expressly incorporated by reference herein in theirentireties.

BACKGROUND

1. Technical Field

The present invention relates to a functional element having a cutoutsection in a wall.

2. Related Art

Recently, there has been developed, a functional element (a physicalquantity sensor) which detects a physical quantity such as anacceleration using, for example, a technique of a silicon micro electromechanical systems (MEMS).

For example, JP-A-2001-330623 describes a physical quantity sensor whichhas a configuration in which two ends of a rectangular weight sectionare integrally coupled with an anchor section through a beam section soas to detect an acceleration and the like, based on a variation incapacitance between a movable electrode and a stationary electrode whichare formed in both sides of the weight section.

In the physical quantity sensor described above, however, there may be acase where a material of the anchor (a stationary section) is differentfrom that of a member (substrate) to which the anchor is fixed. For thisreason, there may be a case where stress occurs in a bonding section ofthe stationary section which is bonded to the substrate, due to adifference between a linear expansion coefficient of the substrate and alinear expansion coefficient of the stationary section. When the beamsection (an elastic section) is sensitive to a characteristic of thephysical quantity sensor and is provided near to the bonding section, amagnitude of the stress generated on the bonding section changesaccording to an ambient temperature of the physical quantity sensor.Therefore, a temperature characteristic of the physical sensor isdegraded.

SUMMARY

An advantage of some aspects of the invention is to provide a functionalelement which can have an excellent temperature characteristic. Further,another advantage of some aspects of the invention is to provide anelectronic apparatus or a mobile entity which includes the functionalelement described above.

The invention can be realized in the following form or applicationexamples.

Application Example 1

According to this application example, there is provided a functionalelement including: a substrate which is provided with a concave section;a stationary section connected to a wall section that defines theconcave section of the substrate; an elastic section which extends fromthe stationary section and is capable of stretching and contracting in afirst axis direction; a movable body connected to the elastic section; amovable electrode section which extends from the movable body; and astationary electrode section which is connected to the substrate andextends in an extending direction of the movable electrode section.Herein the concave section includes a cutout section which is providedon the wall section, the stationary section includes an overlap sectionwhich is spaced with the substrate, and overlaps the concave sectionwhen seen in a plan view, at least a portion of the overlap sectionoverlaps the cutout section when seen in the plan view, and the elasticsection extends from the overlap section.

In the functional element, when seen in the plan view, a distance (theshortest length) from a boundary between the bonding section of thestationary section bonded to the substrate and the overlap section to aboundary between the overlap section and the elastic section can be madelonger while the distance passes through the overlap section, comparedwith a case where the cutout section is not provided. Therefore, when astress occurs on the bonding section of the stationary section which isbonded to the substrate due to a difference between a linear expansioncoefficient of the substrate and a linear expansion coefficient of thestationary section, it is possible to decrease an influence that thestress may exert upon the elastic section. As a result, the functionalelement can have an excellent temperature characteristic.

Application Example 2

In the functional element according to the application example, it ispreferable that the stationary section includes an extension sectionwhich extends from the overlap section in a second axis directionintersecting with the first axis direction when seen in the plan view.

In the functional element, when seen in the plan view, the stationarysection can have a large area of the bonding section bonded to thesubstrate and also can be further stably fixed to the substrate,compared with a case where the extension section is not provided.

Application Example 3

In the functional element according to the application example, it ispreferable that a width of the cutout section in the first axisdirection is wider than a width of the portion of the overlap sectionoverlapping the cutout section in the first axis direction when seen inthe plan view.

In the functional element, when a stress occurs on the bonding sectionof the stationary section which is bonded to the substrate due to adifference between a linear expansion coefficient of the substrate and alinear expansion coefficient of the stationary section, it is possibleto further decrease an influence that the stress may exert upon theelastic section.

Application Example 4

In the functional element according to the application example, it ispreferable that a material of the substrate is glass, and a material ofthe stationary section is silicon.

In the functional element, the silicon substrate is subjected to themachining process so as to be able to form the movable body, and thesilicon substrate for forming the movable body can be bonded to thesubstrate through an anodic bonding.

Application Example 5

In the functional element according to the application example, it ispreferable that the concave section is continuous with the cutoutsection and includes a receiving section which receives the movablebody. When seen in the plan view, the overlap section includes a firstportion overlapping the cutout section and a second portion overlappingthe receiving section. Further, it is preferable that when seen in theplan view, a width of the cutout section in the second axis directionwhich intersects the first axis direction is wider than a width of thesecond portion in the second axis direction.

In the functional element, when seen in a plan view, and when a stressoccurs on the bonding section of the stationary section which is bondedto the substrate due to a difference between a linear expansioncoefficient of the substrate and a linear expansion coefficient of thestationary section, it is possible to further decrease an influence thatthe stress may exert upon the elastic section.

Application Example 6

According to this application example, there is provided an electronicapparatus including any one of the functional elements described above.

The electronic apparatus includes any one of the functional elementsdescribed above so as to be capable of having an excellent temperaturecharacteristic.

Application Example 7

According to this application example, there is provided a mobile entityincluding any one of the functional elements described above.

The mobile entity includes any one of the functional elements describedabove so as to be capable of having an excellent temperaturecharacteristic.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a schematic plan view showing a functional element accordingto the embodiment.

FIG. 2 is a schematic sectional view showing a functional elementaccording to the embodiment.

FIG. 3 is a schematic sectional view showing a manufacturing process ofthe functional element according to the embodiment.

FIG. 4 is a schematic sectional view showing a manufacturing process ofthe functional element according to the embodiment.

FIG. 5 is a schematic sectional view showing a manufacturing process ofthe functional element according to the embodiment.

FIG. 6 is a schematic plan view showing a functional element accordingto the first modification example of the embodiment.

FIG. 7 is a schematic plan view showing a functional element accordingto the second modification example of the embodiment.

FIG. 8 is a schematic perspective view showing an electronic apparatusaccording to the embodiment.

FIG. 9 is a schematic perspective view showing an electronic apparatusaccording to the embodiment.

FIG. 10 is a schematic perspective view showing an electronic apparatusaccording to the embodiment.

FIG. 11 is a schematic perspective view showing a mobile entityaccording to the embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the preferable embodiments of the invention will bedescribed in detail with reference to the accompanied drawings. Theembodiments to be described below do not limit contents of the inventiondescribed in claims improperly. Further, the essential configurationcondition of the invention is not limited to all of the configurationsto be described below.

1. Functional Element

Firstly, a functional element according to the embodiment will bedescribed with reference to the accompanied drawings. FIG. 1 is aschematic plan view showing a functional element 100 according to theembodiment. FIG. 2 is a sectional view of line II-II in FIG. 1 whichshows the functional element 100 according to the embodiment. Further,FIG. 1 and FIG. 2 show an X axis (the first axis), a Y axis (the secondaxis), and a Z axis (the third axis) as three axes which are orthogonalto each other.

As shown in FIG. 1 and FIG. 2, the functional element 100 includes asubstrate 10, a movable body 20, stationary sections 30 a and 30 b,elastic sections 40 and 44, movable electrode sections 50 and 52,stationary electrode sections 60, 62, 64, and 66, wirings 71, 72, and73, pads 74, 75, and 76, and lid body 80. For convenience, the lid body80 is shown in a see-through manner in FIG. 1. Hereinafter, thefunctional element 100 is assumed to be a physical quantity sensor.Specifically, an example will be described in which the functionalelement 100 is an acceleration sensor (MEMS acceleration sensor ofcapacitance type) that detects acceleration of a horizontal direction(the X axis direction (the first axis direction)).

A material of the substrate 10 is, for example, glass, or silicon. Aconcave section 12 is provided on the top surface 11 of the substrate 10(a surface facing toward the +Z axis direction). The substrate 10includes a wall section that defines the concave section 12.Specifically, the wall section 13 defines a plane shape of the concavesection (a shape when seen from the Z axis direction). When seen in theplan view (when seen from the Z axis direction), the wall section 13surrounds the concave section 12. The concave section 12 includes areceiving section 14 and a cutout section 16.

The receiving section 14 is a space that receives the movable body 20,the elastic sections 40 and 44, and the movable electrode sections 50and 52 (hereinafter referred to as “the movable body 20 and the like”).Specifically, as shown in FIG. 2, the receiving section 14 forms acavity 82 that receives the movable body 20 and the like so as toreceive the movable body 20 accordingly. The cavity 82 is defined by thesubstrate 10 and the lid body 80. When seen in the plan view, thereceiving section 14 is overlapped with the movable body 20 and thelike. In the example shown in FIG. 1, the plane shape of the receivingsection 14 is rectangular. The receiving section 14 is continuous to thecutout section 16.

The wall section 13 is provided with the cutout section 16. The cutoutsection 16 is provided as two sections. For, example, one cutout section16 a is provided on the receiving section 14 in the −X axis directionthereof, whereas the other cutout section 16 b is provided on thereceiving section 14 in the +X axis direction. In the example shown, oneside of the wall section 13 is hollowed toward the +X axis direction toform the cutout section 16 a, and the other side of the wall section 13is hollowed toward the −X axis direction to form the other cutoutsection 16 b. In the example shown, the plane shape of the cutoutsection 16 is rectangular. The width (size) of the cutout section 16 inthe X axis direction is narrower (smaller) than that of the receivingsection 14 in the X axis direction. The width of the cutout section 16in the second axis direction (the Y axis direction) is narrower thanthat of the receiving section 14 in the Y axis direction.

The top surface 11 of the substrate 10 is further provided with groovesections 17, 18 and 19. The groove sections 17, 18 and 19 are providedwith wirings 71, 72 and 73, and pads 74, 75 and 76, respectively.

Further, in the example as shown in FIG. 2, a side of the substrate 10which defines the concave section 12 and the groove sections 17, 18 and19 is orthogonal to the top surface 11. However, the side of thesubstrate 10 which defines the concave section 12 and the groovesections 17, 18 and 19 may be inclined to the top surface 11.

The movable body 20, the stationary sections 30 a and 30 b, the elasticsections 40 and 44, and the movable electrode sections 50 and 52 aretogether integrally formed. For example, one piece of the substrate (asilicon substrate 102, see FIG. 4) is subjected to a patterning processto integrally altogether form the movable body 20, the stationarysections 30 a and 30 b, the elastic sections 40 and 44, and the movableelectrode sections 50 and 52. The material for the movable body 20, thestationary sections 30 a and 30 b, the elastic sections 40 and 44, andthe movable electrode sections 50 and 52 is, for example, a siliconwhich is subjected to a doping process with impurities such asphosphorus or boron so as to have conductivity. The material of thestationary sections 30 a and 30 b is different from that of thesubstrate 10.

The movable body 20 is connected to the elastic sections 40 and 44 andis displaceable along with the X axis direction. Specifically, themovable body 20 is displaced in the X axis direction while elasticallydeforming the elastic sections 40 and 44, in response to acceleration inthe X axis direction. According to such a displacement, gaps between themovable electrode sections 50 and 52 and the stationary electrodesections 60, 62, 64 and 66 change in sizes thereof. In other words,according to such a displacement, capacitances between the movableelectrode sections 50 and 52 and the stationary electrode sections 60,62, 64 and 66 changes in magnitudes thereof. Based on the capacitances,the functional element 100 detects the acceleration in the X axisdirection. In the example shown in FIG. 1, the plane shape of themovable body 20 is a rectangular shape having long sides in the X axis.

The first stationary section 30 a and the second stationary section 30 bare connected to the wall section 13 of the substrate 10. Specifically,the stationary sections 30 a and 30 b have a bonding section 31 bondedto the substrate 10 and thus is bonded to substrate 10 through thebonding section 31. The plane shape of the bonding section 31 is thesame as that of a contact surface between the stationary sections 30 aand 30 b and the substrate 10. The stationary sections 30 a and 30 b arefixed on the substrate 10. The first stationary section 30 a is locatedin the −X axis direction with respect to the receiving section 14. Thesecond stationary section 30 b is located in the +X axis direction withrespect to the receiving section 14. The stationary sections 30 a and 30b have an overlap section 32 which overlaps the concave section 12 whenseen in the plan view.

The overlap section 32 is spaced with the substrate 10. At least aportion of the overlap section 32 overlaps the cutout section 16 whenseen in the plan view. In the example shown, the overlap section 32includes a first portion 33 overlapping the cutout section 16 and asecond portion 34 overlapping the receiving section 14, when seen in theplan view. The first portion 33 is connected to the bonding section 31.The second section 34 is connected to the first portion 33. In theexample shown, the plane shape of the first portion 33 and the planeshape of the second portion 34 are rectangular. When seen in the planview, a width A of the cutout section 16 in the Y axis direction iswider (larger) than a width B of the second portion 34 in the Y axisdirection.

The first stationary section 30 a and the second stationary section 30 bhave extension sections 35 and 36 which extend from the first portion 33of the overlap section 32 in the Y axis direction. In the example shown,the extension section 35 extends from the first portion 33 in the +Yaxis direction, and the extension section 36 extends from the firstportion 33 in the −Y axis direction. At least a portion of the extensionsections 35 and 36 constitutes the bonding section 31. In the exampleshown, the extension section 35 of the first stationary section 30 a andthe extension sections 35 and 36 of the second stationary section 30 bconstitutes the bonding section 31. Except for a portion which overlapsthe groove section 19 and a contact section 70, the extension section 36of the first stationary section 30 a constitutes the bonding section 31when seen in the plan view.

As shown in FIG. 1, the bonding section 31 of the first stationarysection 30 a has an area 31 a which is located in the −X axis directionwith respect to the first portion 33 of the overlap section 32. Thebonding section 31 of the second stationary section 30 b has an area 31b which is located in the +X axis direction with respect to the firstportion 33 of the overlap section 32.

The first elastic section 40 extends from the first stationary section30 a, and is capable of stretching and contracting in the X axisdirection. Specifically, the first elastic section 40 extends from thesecond portion 34 of the overlap section 32 of the first stationarysection 30 a. The first elastic section 40 couples the movable body 20with the first stationary section 30 a. The second elastic section 44extends from the second stationary section 30 b to be capable ofstretching and contracting in the X axis direction. Specifically, thesecond elastic section 44 extends from the second portion 34 of theoverlap section 32 of the second stationary section 30 b. The secondelastic section 44 couples the movable body 20 with the secondstationary section 30 b.

The first elastic section 40 and the second elastic section 44 isconfigured to have a predetermined spring constant and to displace themovable body 20 in the X axis direction. In the example shown, the firstelastic section 40 is configured to include beams 41 and 42 whichreciprocate in the Y axis direction and extend in the X axis direction.The second elastic section 44 is configured to include beams 45 and 46which reciprocate in the Y axis direction and extend in the X axisdirection.

The first movable electrode section 50 and the second movable electrodesection 52 extend from the movable body 20 in opposing directions alongthe Y axis direction. Specifically, the first movable electrode section50 extends from the movable body 20 in the +Y axis direction. The secondmovable electrode section 52 extends from the movable body 20 in the −Yaxis direction. The movable electrode sections 50 and 52 are arranged asplural pieces in parallel in the X axis direction, respectively. In theexample shown, the plane shape of the movable electrode sections 50 and52 is a rectangular shape having long sides in the Y axis. The movableelectrode sections 50 and 52 can be displaced in the X axis according tothe displacement of the movable body 20.

The first stationary electrode section 60 and the second stationaryelectrode section 62 are disposed to face the first movable electrodesection 50. Specifically, the first stationary electrode section 60 isdisposed to face the first movable electrode section 50 on one side (the−X axis direction) of the first movable electrode section 50. The secondstationary electrode section 62 is disposed to face the first movableelectrode section 50 on the other side (the +X axis direction) of thefirst movable electrode section 50. The stationary electrode sections 60and 62 are connected to the substrate 10, and extend to be disposedalong the extending direction (the Y axis direction) of the movableelectrode section 50. In the example shown, when seen in the plan view,the stationary electrode sections 60 and 62 extend from a portion whichis bonded to the top surface 11 of the substrate 10, and go beyond anouter edge of the concave section 12 so as to further extend to themovable body 20. The plane shape of the stationary electrode sections60, 62 is a rectangular shape having long sides in the Y axis. Thestationary electrode sections 60 and 62 have the same material as thatof the movable body 20.

The third stationary electrode section 64 and the fourth stationaryelectrode section 66 are disposed to face the second movable electrodesection 52. Specifically, the third stationary electrode section 64 isdisposed to face the second movable electrode section 52 on one side(the −X axis direction) of the second movable electrode section 52. Thefourth stationary electrode section 66 is disposed to face the secondmovable electrode section 52 on the other side (the +X axis direction)of the second movable electrode section 52. The stationary electrodesections 64 and 66 are connected to the substrate 10, and extend in theextending direction (the Y axis direction) of the movable electrodesection 52. In the example shown, when seen in the plan view, thestationary electrode sections 64 and 66 extend from a portion which isbonded to the top surface 11 of the substrate 10, and go beyond an edgeof the concave section 12 to further extend to the movable body 20. Theplane shape of the stationary electrode sections 64 and 66 is arectangular shape having long sides in the Y axis. The stationaryelectrode sections 64 and 66 have the same material as that of themovable body 20.

The first wiring 71 is provided on the substrate 10. Specifically, thefirst wiring 71 is disposed on the groove section 17 which is formed onthe top surface 11 of the substrate 10. The first wiring 71 iselectrically connected to the stationary electrode sections 60 and 64through the contact section 70. In other words, the stationary electrodesections 60 and 64 are electrically connected to each other.

The second wiring 72 is provided on the substrate 10. Specifically, thesecond wiring 72 is disposed on the groove section 18 which is formed onthe top surface 11 of the substrate 10. The second wiring 72 iselectrically connected to the stationary electrode sections 62 and 66through the contact section 70. In other words, the stationary electrodesections 62 and 66 are electrically connected to each other.

The third wiring 73 is provided on the substrate 10. Specifically, thethird wiring 73 is disposed on the groove section 19 which is formed onthe top surface 11 of the substrate 10. The third wiring 73 iselectrically connected to the first stationary section 30 a through thecontact section 70. In the example shown, the contact section 70 thatelectrically connects the third wiring 73 with the first stationarysection 30 a is connected to the extension section 36 of the firststationary section 30 a.

The pads 74, 75 and 76 are provided on the substrate 10. Specifically,the pads 74, 75 and 76 are respectively disposed on the groove sections17, 18 and 19 to be connected to the wirings 71, 72 and 73. When in theplan view, the pads 74, 75 and 76 are located not to be overlapped withthe lid body 80. In the example shown, the pads 74, 75 and 76 arearranged in parallel in the Y axis direction.

The materials for the wirings 71, 72 and 73, the pads 74, 75 and 76, andthe contact section 70 (hereinafter, referred to as “the wiring 71 andthe like”) include, for example, indium tin oxide (ITO), aluminum, gold,platinum, titanium, tungsten, and chrome. When the material of thewiring 71 and the like is transparent electrode material such as ITO,and also when the substrate 10 is transparent, foreign matter which ispresent on the wiring 71 and the like can be easily and visuallyidentified when seen from the bottom surface (a surface opposite to thetop surface 11) of the substrate 10.

The lid body 80 is provided on the substrate 10. The substrate 10 andthe lid body 80 constitute a package. As shown in FIG. 2, the substrate10 and the lid body 80 form a cavity 82. The movable body 20 and thelike are received in the cavity 82. As shown in FIG. 2, a gap 2 betweenthe third wiring 73 and the lid body 80 (a gap between the lid body 80and the substrate 10, and the gap formed of the groove section 19) maybe filled with an adhesive member (not shown) and the like. In thiscase, the cavity 82 may be sealed to be in an inert gas (for exampleNitrogen gas) environment. The material of the lid body 80 includes, forexample, silicon or glass.

The functional element 100 uses the pads 74 and 76 to be capable ofmeasuring a capacitance between the first movable electrode section 50and the first stationary electrode section 60, and a capacitance betweenthe second movable electrode section 52 and the third stationaryelectrode section 64. Further, the functional element 100 uses the pads75 and 76 to be capable of measuring a capacitance between the firstmovable electrode section 50 and the second stationary electrode section62, and a capacitance between the second movable electrode section 52and the fourth stationary electrode section 66. As described above, thefunctional element 100 individually measures and performs a differentialdetection on (using so called the differential detection method) thecapacitance between the movable electrode sections 50 and 52 and thestationary electrode sections 60 and 64, and the capacitance between themovable electrode sections 50 and 52 and the stationary electrodesections 62 and 66, and thereby can detect the acceleration.

The functional element 100 has characteristics as follows, for example.

In the functional element 100, the concave section 12 includes thecutout section 16 which is provided on the wall section 13, and thestationary sections 30 a and 30 b include the overlap section 32 whichis spaced with the substrate 10 and overlaps the concave section 12 whenin the plan view. At least a portion of the overlap section 32 overlapsthe cutout section 16 when seen in the plan view. The elastic sections40 and 44 extend from the overlap section 32. For this reason, in thefunctional element 100, when seen in the plan view, a distance (theshortest length) L1 from a boundary 3 between the bonding section 31 andthe overlap section 32 to a boundary 4 between the overlap section 32and the first elastic section 40 can be made longer while the distancepasses through the overlap section 32 of the first stationary section 30a, compared with a case where the cutout section 16 a is not provided.Therefore, when a stress occurs on the bonding section 31 of the firststationary section 30 a due to a difference between a linear expansioncoefficient of the substrate 10 and a linear expansion coefficient ofthe first stationary section 30 a, it is possible to decrease aninfluence that the stress may exert upon the first elastic section 40.Similarly to this, in the functional element 100, when seen in the planview, a distance (the shortest length) L2 from a boundary 3 between thebonding section 31 and the overlap section 32 to a boundary 5 betweenthe overlap section 32 and the second elastic section 44 can be madelonger while the distance passes through the overlap section 32 of thesecond stationary section 30 b, compared with a case where the cutoutsection 16 b is not provided. Therefore, when a stress occurs on thebonding section 31 of the second stationary section 30 b due to adifference between a linear expansion coefficient of the substrate 10and a linear expansion coefficient of the second stationary section 30b, it is possible to decrease an influence that the stress may exertupon the second elastic section 44. As a result, the functional element100 can have an excellent temperature characteristic. When seen in theplan view, the distance L1 between the boundary 3 and the boundary 4 ina case where the distance L1 passes through the overlap section 32 ofthe first stationary section 30 a, and the distance L2 between theboundary 3 and the boundary 5 in a case where the distance L2 passesthrough the overlap section 32 of the second stationary section 30 bare, for example, greater than or equal to 20 μm.

For example, when the cutout section is not provided and the width ofthe second potion of the overlap section in the X axis direction isincreased to lengthen the distance from the boundary between the bondingsection and the overlap section to the boundary between the overlapsection and the elastic section, there may be a case where it isdifficult to miniaturize the functional element. It is possible tominiaturize the functional element 100 by provision of the cutoutsection 16.

In the functional element 100, the stationary sections 30 a and 30 bincludes the extension sections 35 and 36 which extend from the overlapsection 32 in the Y axis direction when seen in the plan view. For thisreason, when seen in the plan view, the stationary sections 30 a and 30b can have a large area of the bonding section 31 and can also befurther stably fixed to the substrate 10, compared with a case where theextension sections 35 and 36 are not provided.

In the functional element 100, the material of the substrate 10 is, forexample, glass, and the material of the stationary sections 30 a and 30b is, for example, silicon. For this reason, the silicon substrate issubjected to the machining process so that the movable body 20 may beformed, and the silicon substrate for forming the movable body 20 can bebonded to the substrate 10 through an anodic bonding. Further, in thefunctional element 100, even in the case that the material of thesubstrate 10 is different from that of the stationary sections 30 a and30 b, as described above, when a stress occurs on the bonding section 31of the stationary sections 30 a and 30 b due to a difference between alinear expansion coefficient of the substrate 10 and a linear expansioncoefficient of the stationary sections 30 a and 30 b, it is possible todecrease an influence that the stress may exert upon the elasticsections 40 and 44.

In the functional element 100, when seen in the plan view, the width Aof the cutout sections 16 in the Y axis direction is wider than thewidth B of the second portion 34 of the overlap section 32 in the Y axisdirection. For this reason, in the functional element 100, when seen inthe plan view, the distance L1 between the boundary 3 and the boundary 4in a case where the distance L1 passes through the overlap section 32 ofthe first stationary section 30 a, and the distance L2 between theboundary 3 and the boundary 5 in a case where the distance L2 passesthrough the overlap section of the second stationary section 30 b can bemade longer, compared with a case where the width A is narrower than thewidth B. Therefore, when a stress occurs on the bonding section 31 dueto a difference between a linear expansion coefficient of the substrate10 and a linear expansion coefficient of the stationary sections 30 aand 30 b, it is possible to decrease an influence that the stress mayexert upon the elastic sections 40 and 44.

In the functional element 100, the contact section 70 that electricallyconnects the third wiring 73 with the first stationary section 30 a isconnected to the extension section 36 of the first stationary section 30a. For this reason, in the functional element 100, when a stress occurson the first stationary section 30 a due to a connection of the contactsection 70, it is possible to further decrease an influence that thestress may exert upon the first elastic section 40, compared with, forexample, the contact section for electrically connecting the thirdwiring with the first stationary section connected to the overlapsection closer to the elastic section.

2. Manufacturing Method of Functional Element

Hereinafter, a manufacturing method of the functional element accordingto the embodiment will be described with reference to the accompanieddrawings. FIG. 3, FIG. 4 and FIG. 5 are schematic sectional viewsshowing a manufacturing process of the functional element 100 accordingto the embodiment, and the views correspond to FIG. 2.

As shown in FIG. 3, for example, the glass substrate is subjected to thepatterning process (specifically, by performing a patterning based onphotolithography and an etching) to form the concave section 12 havingthe receiving section 14 and the cutout section 16, and to further formthe groove sections 17, 18 and 19. With this process used, it ispossible to obtain the substrate 10 in which the concave section 12, andthe groove sections 17, 18 and 19 are formed.

Further, the wirings 71, 72 and 73 are formed in the groove sections 17,18 and 19, respectively. Subsequently, the contact section 70 is formedon the wirings 71, 72 and 73. Still subsequently, the pads 74, 75 and 76are formed to be connected to the wirings 71, 72 and 73, respectively.Films are formed using, for example, a spattering method, or chemicalvapor deposition (CVD) and the patterning process is performed tothereby form the contact section 70, the wirings 71, 72 and 73, and thepads 74, 75 and 76. The process for forming the contact section 70 andthe process for forming the pads 74, 75 and 76 carry on regardless ofthe order thereof.

It is preferable that the contact section 70 is formed to protrudeupwardly higher than the top surface 11 of the substrate 10. With thisconfiguration, the contact section 70 can be reliably contacted to thesilicon substrate 102 to be described later. In this case, the contactsection 70 may be deformed during, for example, a process for bondingthe silicon substrate 102 to the substrate 10.

As shown in FIG. 4, for example, the silicon substrate 102 is bonded tothe substrate 10. The bonding between the substrate 10 and the siliconsubstrate 102 is performed using, for example, an anodic bonding.Therefore, it is possible that the silicon substrate 102 is stronglybonded to the substrate 10.

As shown in FIG. 5, for example, a grinding machine is used to grind andthin the silicon substrate 102. After that, the thinned siliconsubstrate is subjected to the patterning process to have a predeterminedshape, and thus the movable body 20, and the stationary sections 30 aand 30 b, the elastic sections 40 and 44, and the movable electrodesections and 52 are integrally formed. Further, in this process, thestationary electrode sections 60, 62, 64 and 66 are formed. The etchingof the patterning according to this process may be performed using theBosch method.

As shown in FIG. 2, the lid body 80 is bonded to the substrate 10, andthe movable body 20 and the like are received in a cavity 82 formed bythe substrate 10 and the lid body 80. The bonding between the substrate10 and the lid body 80 is performed using, for example, the anodicbonding. Therefore, it is possible that the lid body 80 is stronglybonded to the substrate 10. This process may be performed in an inertgas environment to be able to fill the cavity 82 with the inert gas.

With the process described above, the functional element 100 ismanufactured.

3. Modification Example 3.1. First Modification Example

Hereinafter, a functional element according to the first modificationexample of the embodiment will be described with reference to theaccompanied drawings. FIG. 6 is a schematic plan view showing afunctional element 200 according to the first modification example ofthe embodiment. In FIG. 6, and in FIG. 7 to be described later, the lidbody 80 is shown in a see-through manner. Further, FIG. 6 and FIG. 7 tobe described later show an X axis (the first axis), a Y axis (the secondaxis), and a Z axis (the third axis) as three axes which are orthogonalto each other.

In the functional element 200 according to the first modificationexample of the embodiment, the like numbers will be assigned to themembers having the same function as those in the functional element 100according to the embodiment and the detailed description thereof willnot be repeated. The same also applies to the functional element 300according to the second modification example of the embodiment.

In the functional element 100 describe above, when seen in the plan viewas shown in FIG. 1, the width of the cutout section 16 in the X axisdirection is the same as that of the first portion 33 of the overlapsection 32 in the X axis direction, the bonding section 31 of the firststationary section 30 a has an area 31 a, and the bonding section 31 ofthe second stationary section 30 b has an area 31 b.

Whereas, in the functional element 200, when seen in the plan view asshown in FIG. 6, the width C of the cutout section 16 in the first axisdirection (the X axis direction) is wider than the width D of a portion(the first portion) 33 overlapping the cutout section 16 in the X axisdirection when seen in the plan view, the first portion 33 being a partof the overlap section 32. For this reason, the bonding section of thefirst stationary section 30 a does not include an area which is locatedin the first portion 33 of the overlap section 32 in the −X axisdirection. Similarly, the bonding section 31 of the second stationarysection 30 b does not include an area which is located in the firstportion 33 of the overlap section 32 in the +X axis direction.Therefore, in the functional element 200, when a stress occurs on thebonding section 31 due to a difference between a linear expansioncoefficient of the substrate 10 and a linear expansion coefficient ofthe stationary sections 30 a and 30 b, it is possible to decrease aninfluence that the stress may exert upon the elastic sections 40 and 44,for example, compared with the case of the functional element 100.

3.2. Second Modification Example

Hereinafter, a functional element according to the second modificationexample of the embodiment will be described with reference to theaccompanied drawings. FIG. 7 is a schematic plan view showing thefunctional element 300 according to the second modification example ofthe embodiment.

In the functional element 100 described above, as shown in FIG. 1, thefirst stationary section 30 a and the second stationary section 30 binclude the overlap section 32 in the central portion in the Y axisdirection.

Whereas, in the functional element 300, as shown in FIG. 7, the firststationary section 30 a and the second stationary section 30 b includethe overlap section 32 in the end portion in the Y axis direction. Whenseen in a plan view, the cutout section 16 a overlapped with the firststationary section 30 a is provided as two pieces. Further, when seen ina plan view, the cutout section 16 b overlapped with the secondstationary section 30 b is provided as two pieces. In the example shown,the overlap section 32 disposed on the end portion of the firststationary section 30 a in the +Y axis direction is connected to thebeam 41 of the first elastic section 40, and the overlap section 32disposed on the end portion of the first stationary section 30 a in the−Y axis direction is connected to the beam 42 of the first elasticsection 40. Further, the overlap section 32 disposed on the end portionof the second stationary section 30 b in the +Y axis direction isconnected to the beam 45 of the second elastic section 44, and theoverlap section 32 disposed on the end portion of the second stationarysection 30 b in the −Y axis direction is connected to the beam 46 of thesecond elastic section 44. In the example shown, the overlap section isconfigured to include the first portion 33 overlapping the cutoutsection 16 when seen in the plan view.

In the functional element 300, the first stationary section 30 aincludes an extension section 37 which extends in the Y axis directionfrom the overlap section 32 disposed on the end portion of the +Y axisdirection to the overlap section 32 disposed on the end of the −Y axisdirection. Similarly, the second stationary section 30 b includes anextension section 37 which extends in the Y axis direction from theoverlap section 32 disposed on the end portion of the +Y axis directionto the overlap section 32 disposed on the end portion of the −Y axisdirection.

Similarly to the functional element 100, the functional element 300 canhave an excellent temperature characteristic.

As shown in the functional element 200 in FIG. 6, also in the functionalelement 300, the width of the cutout section 16 in the X axis directionmay be wider than width of the first portion 33 of the overlap section32 in the X axis direction.

4. Electronic Apparatuses

Hereinafter, electronic apparatuses according to the embodiment will bedescribed with reference to the accompanied drawings. The electronicapparatus according to the embodiment includes the functional elementaccording to one aspect of the invention. Hereinafter, an electronicapparatus including the functional element 100 as a functional elementaccording to one aspect of the invention will be described.

FIG. 8 is a schematic perspective view showing a mobile type (ornotebook type) personal computer 1100 as the electronic apparatusaccording to the embodiment.

As shown in FIG. 8, the personal computer 1100 is configured to includea main body section 1104 having a keyboard 1102, and a display unit 1106having a display section 1108. The display unit 1106 is rotatablysupported to the main body section 1104 through a hinge structuresection.

Such a personal computer 1100 includes the built-in functional element100.

FIG. 9 is a schematic perspective view showing a mobile phone (alsoincluding PHS) 1200 as the electronic apparatus according to theembodiment.

As shown in FIG. 9, the mobile phone 1200 includes plural operatingbuttons 1202, an earpiece 1204, and a mouthpiece 1206. A display section1208 is disposed between the operating button 1202 and the earpiece1204.

Such a mobile phone 1200 includes the built-in functional element 100.

FIG. 10 is a schematic perspective view showing a digital still camera1300 as the electronic apparatus according to the embodiment. Further,in FIG. 10, a connection with an external device is also briefly shown.

Generally, in a typical camera, a light image of a subject causes asilver salt photographic film to be exposed to light, whereas thedigital still camera 1300 performs a photoelectric conversion on a lightimage of a subject using an imaging element such as a charge coupleddevice (CCD) so as to generate an imaging signal (an image signal).

A display section 1310 is provided on the rear surface of the case(body) 1302 in the digital still camera 1300 and is configured toperform a displaying process based on the imaging signal generated bythe CCD. Further, the display section 1310 functions as a finderdisplaying a subject as an electronic image.

Further, a light receiving section 1304 including optical lenses(imaging optical system), CCD or the like is provided on the front side(rear side in the drawing) of the case 1302.

If a photographer notices a subject image displayed on the displaysection 1310 and presses the shutter button 1306, an imaging signal ofthe CCD at that time is transmitted to and stored in a memory 1308.

Further, a video signal output terminal 1312 and an input-outputterminal 1314 for data communication are provided on a side of the case1302 in the digital still camera 1300. Further, the video signal outputterminal 1312 may be connected with a television monitor 1430, and theinput-output terminal 1314 for data communication may be connected witha personal computer 1440, respectively, if necessary. Further, aconfiguration is provided in which a predetermined operation causes theimaging signal stored in the memory 1308 to be output to the televisionmonitor 1430 or the personal computer 1440.

Such a digital still camera 1300 includes the built-in functionalelement 100.

The electronic apparatuses 1100, 1200, and 1300 include the functionalelement 100 to thereby be capable of having an excellent temperaturecharacteristic.

In addition to the personal computer (the mobile type personal computer)as shown in FIG. 8, the mobile phone as shown in FIG. 9, and the digitalstill camera as shown in FIG. 10, the electronic apparatuses having thefunctional element 100 may be applied to for example, an ink jet typedischarging device (for example, an ink jet printer), a laptop typepersonal computer, a television, a video camera, a video tape recorder,various type navigation devices, a pager, an electronic notebook (alsoincluding a communicative function), an electronic dictionary, anelectronic calculator, an electronic game device, a head mount display,a word processor, a work station, a picturephone, a television monitorfor crime prevention, electronic binoculars, a POS terminal, medicalequipment (for example, electronic thermometer, sphygmomanometer, ablood glucose meter, an electrocardiogram measurement device, ultrasonicdiagnostic equipment, or an electronic endoscope), a fishfinder, variousmeasuring equipment, instruments (e.g., instruments of a vehicle, aplane, a rocket and a ship), a posturing control of a robot or the humanbody, a flight simulator, and the like.

5. Mobile Entity

Hereinafter, a mobile entity according to the embodiment will bedescribed with reference to the accompanied drawings. The mobile entityaccording to the embodiment includes the functional element according toone aspect of the invention. Hereinafter, the mobile entity includingthe functional element 100 as the functional element according to oneaspect of the invention will be described.

FIG. 11 is a schematic perspective view showing a car 1500 as a mobileentity according to the embodiment.

The car 1500 includes the built-in functional element 100. Specifically,as shown in FIG. 11, the car body 1502 of the car 1500 is provided withan electronic control unit (ECU) 1504 mounted thereon in which thefunctional element 100 for detecting the acceleration of the car 1500 isbuilt therein to control an output of the engine. Besides, thefunctional element 100 may be widely applied to a control unit forposturing of a car body, an antilock brake system (ABS), an air bag, atire pressure monitoring system (TPMS), and the like.

The car 1500 includes the functional element 100 to thereby be capableof having an excellent temperature characteristic.

The invention is not limited to the embodiments describe above, but mayinclude various types of modification examples without departing fromthe scope of the invention.

For example, the above embodiments describe a case where the functionalelement is an acceleration sensor that detects the acceleration (aphysical quantity sensor) in the X axis direction. However, thefunctional element according to one aspect of the invention may be anacceleration sensor that detects the acceleration in the Y axisdirection, or in the vertical direction (the Z axis direction). Further,the functional element according to one aspect of the invention is notlimited to the acceleration sensor, but may be, for example, a gyrosensor that detects an angular velocity. Further, the functional elementaccording to one aspect of the invention may be an element such as amicro electro mechanical systems (MEMS) vibrator other than a sensorsuch as the acceleration sensor and the angular sensor.

Further, the above embodiments describe that, as three axes, the firstaxis, the second axis and the third axis are orthogonal to each other.However, the first axis, the second axis, and the third axis may not beorthogonal to each other, but may intersect with each other as threeaxes.

The embodiments and the modification examples described above are onlyexamples and the invention is not limited thereto. For example, anycombination may be appropriately and selectively formed from each of theembodiments and each of the modification examples.

The invention includes configurations (for example, configurationshaving the same function, the same way, and the same result, orconfigurations having the same object and the same advantages)substantially the same as the configuration described in the embodimentsof the invention. Furthermore, the invention includes configurationsobtained by replacing a non-essential part of the configurationdescribed in the embodiments of the invention. Furthermore, theinvention includes configurations capable of exerting the samefunctional effects and configurations capable of achieving the sameobject as the configuration described in the embodiments of theinvention. Furthermore, the invention includes configurations obtainedby adding technologies known to the public to the configurationdescribed in the embodiments of the invention.

What is claimed is:
 1. A functional element comprising: a substrate; astationary member that is spaced apart from the substrate; a wall thatis provided between the substrate and the stationary member; an elasticmember that extends from the stationary member; a movable body that isconnected to the elastic member; a movable electrode that is connectedto the movable body; and a stationary electrode that is connected to thesubstrate and that faces the movable electrode, wherein the wallincludes a cutout, the stationary member includes an overlap area whichoverlaps the cutout in a plan view, and the elastic member extends fromthe overlap area of the stationary member in a first axis direction. 2.The functional element according to claim 1, wherein the stationarymember includes an extension section which extends from the overlap areain a second axis direction which intersects with the first axisdirection in the plan view.
 3. The functional element according to claim2, wherein a width of the cutout in the first axis direction is widerthan a width of the overlap area in the cutout in the first axisdirection in the plan view.
 4. The functional element according to claim2, wherein: the substrate has a first area that faces the movable bodyin the plan view, the overlap area has second and third areas, thesecond area overlaps with the cutout in the plan view, and the thirdarea overlaps with the first area in the plan view, and a width of thecutout in a second axis direction which intersects with the first axisdirection is wider than a width of the third area in the second axisdirection.
 5. The functional element according to claim 1, wherein awidth of the cutout in the first axis direction is wider than a width ofthe overlap area in the first axis direction in the plan view.
 6. Thefunctional element according to claim 5, wherein: the substrate has afirst area that faces the movable body in the plan view, the overlaparea has second and third areas, the second area overlaps with thecutout in the plan view, and the third area overlaps with the first areain the plan view, and a width of the cutout in a second axis directionwhich intersects with the first axis direction is wider than a width ofthe third area in the second axis direction.
 7. The functional elementaccording to claim 1, wherein a material of the substrate is glass, anda material of the stationary member is silicon.
 8. The functionalelement according to claim 7, wherein: the substrate has a first areathat faces the movable body in the plan view, the overlap area hassecond and third areas, the second area overlaps with the cutout in theplan view, and the third area overlaps with the first area in the planview, and a width of the cutout in a second axis direction whichintersects with the first axis direction is wider than a width of thethird area in the second axis direction.
 9. The functional elementaccording to claim 1, wherein: the substrate has a first area that facesthe movable body in the plan view, the overlap area has second and thirdareas, the second area overlaps with the cutout in the plan view, andthe third area overlaps with the first area in the plan view, and awidth of the cutout in a second axis direction which intersects with thefirst axis direction is wider than a width of the third area in thesecond axis direction.
 10. An electronic apparatus comprising: thefunctional element according to claim
 1. 11. A mobile entity comprising:the functional element according to claim 1.